Let's assume that time is not infinite, but has boundaries. With that assumption, we can guess at the starting point, which is when quantum soup containing nothing decided to produce a singularity, which immediately -- for lack of better words -- exploded, shooting the most elementary particles outward into every direction, perhaps not into existing volume, but creating volume as it expanded. In short time, these initial particles organized themselves into increasingly more complex subatomic particulate until the small elements began to form; hydrogen, helium, and lithium. Eventually, those fundamental elements coalesced into stars, and nuclear fission commenced, producing the larger elements (up to iron). Heavier elements came later during supernovae. Now we have a starting point, an initial time.
The age of the Universe is suggested through analysis of cosmic background radiation data obtained by WMAP, which allows calculation of the expansion rate of the Universe. Given the calculated expansion rate, scientists were able to extrapolate the age of the universe to within 1% accuracy at 13.73 billion years old. The Universe presumably originated from a singularity to what we see over a span of approximately 13.73 billion years.
|Conceptual model of the observable Universe.|
While we can understand the concept of the Universe, the actually volume is so monumental that we consequently become cognitively overwhelmed. Trying to picture the Universe as we know it is not possible. The sheer size of it makes mental rendering by our minds impractical. The Universe is dozens of billions of light years in diameter. The volume of the Universe we can quantify -- that we can observe -- hinders upon the light that has had time to travel to our observatories. Therefore, the observable universe appears from our perspective to be spherical; the radius from Earth to the observable edges is limited by the speed of light multiplied by the age of the Universe. Other locations distant in the Universe have their own unique observable universe which will not be congruent with the view of the Universe we have on Earth. While the precise shape of the true Universe remains unknown, calculations using the estimated density of the Universe predict a Universe that is nearly flat to within 2% margin of error.
Currently accepted astrophysical calculations show the diameter of the observable universe to be at least 93 billion light years across. That means light that began traveling from one edge of our observable universe would take 93 billion years to travel to the opposite observable edge. Light travels at a constant speed of 186,000 miles per second in vacuum, which boils down to roughly 670 million miles per hour. In a desperate attempt to put the volume of the Universe we can observe into perspective, imagine traveling from one edge of the observable universe to the other at 600 MPH; the upper bound on commercial airliner flight speed. Picturing yourself in that plane? Your journey would take you 37,386,000,000 trillion years, which equates to 2,722,942,462,000 times the currently estimated age of the Universe at 13.73 billion years old.
The majority of the Universe is made up of dark energy. NASA puts the amount of dark energy making up the universe at 70%. Making itself present only as a cosmological constant, not through direct observation. This constant is used to balance the equation of the currently accepted acceleration rate of the expansion of the Universe. Without the presence of this elusive and mysterious dark energy, our current expansion models would not hold weight. Dark energy is necessary to explain the exponentially increasing speed at which the Universe is expanding, otherwise our models predict that the Universe should be shrinking, which we know is not true based on observable data. Without the existence of dark energy, we are forced to abandon our current model for the expansion of the Universe, which cannot be currently replaced.
Another 23% of the Universe is said to be made of dark matter that is inferred to exist from gravitational effects on visible matter, such as how galaxies angular momentum doesn't seem to be conserved. This matter is also undetectable using current methods. The vast majority of the dark matter in the universe is believed to be nonbaryonic, which means that it contains no atoms and does not interact with ordinary matter through the electromagnetic forces we are so familiar with. Dark matter is the source of the gravitational forces required for our cosmological model to work.
My own personal view is that dark matter and dark energy are merely petty ways of forcing a failed model to work. I believe we are in need of a new and revolutionary model, one which does not require the inclusion of undetectable matter & energy to work. There is a huge void separating current theory from direct observation and both sides of the issue seem to have solid arguments. The fiasco remains unresolved after more than 20 years. If someone steps up and solves this problem they will be virtually guaranteed to win a Nobel Prize. It is worth noting that the entire dark matter issue revolves around the force of gravity acting over long distances. There may just be another long-range force that we are currently ignorant of. This whole dark matter explanation may later be laughed at; akin to the days of people not believing the Earth was round.
Let's switch gears from looking out into the vastness of the Cosmos to examining the matter we are made of and we interact with. The more a person zooms into solid matter, the more absurd things get. At the quantum level, matter dissolves from our perception of seeming structural integrity and becomes a bizarre dance of subatomic particles that seem to bounce in-and-out of reality. While these particles appear to have complete integrity on the macroscopic level, in reality they are made up overwhelmingly of empty space. Although you can reach and touch a nearby wooden object and are unable to push your finger through it, it is home to 99.9999999999999% empty space, with 99.9% of the mass concentrated in the microscopic elements nuclei.
This places our own perceptions in between two ferocious cognitive monsters; a volume of space so large as to be unimaginable, pushed around by forces we don't fully understand, and particles so small as to be undetectable, which seem to blink in-and-out of existence.
Try now to think about how desolate the Universe is. The nearest star in our own galaxy is Alpha Centauri, which is more than 4.2421 light years away. That means the light you see from Alpha Centauri at night has been traveling for at least 4 years before it enters your retina to be analyzed by your brain's optic nerve. The nearest galaxy, The Canis Major Dwarf Galaxy, is 25,000 light years away from our solar system. Alternatively, Canis Major Dwarf is 42,000 light years away from the center of our own galaxy, the Milky Way. This distance between the galaxies is ever-increasing by universal expansion.
The Hubble telescope was recently outfitted with an advanced new lens. Scientists then pointed the updated scope at a tiny patch of the sky the size of a dime held out at arm's length. The first images to come back were absolutely awe-inspiring; there were 10,000 visible galaxies in the photo. Each one can have over 1,000,000,000,000 stars. That means in this tiny patch of sky there are approximately 10,000,000,000,000,000 stars.
|Sample of the Hubble Ultra Deep Field image, perhaps the most important image ever created.|
Trying to integrate these facts into your mind is nonsensical and therein lie the point of my discussion; we are simply unable to fully comprehend the objective reality. Despite our assumption of being the special, sentient, & intellectual top dogs in the Universe, we are ill-equipped to visually grasp the desolate nature of our Universe (both macro- and microscopically).
A multiverse can be thought of as a conglomerate of universes stuck together, much like the way bubbles often congregate. The possible existence of a multiverse allows for an infinite number of universes, some of which may have foreign physical laws. Some scientists believe that alternate universes exist in which the building blocks of atoms never formed atoms at all. An alternative vision is that of a universe in which nothing beyond hydrogen and helium ever formed. On the flip size, zeroverse theory suggests that there is actually no Universe at all, and our entire perception is merely derivative of quantum reality collapsing where it is observed. Take a moment to ponder these strange scientific views on your own, but keep in mind that question of whether or not a multiverse or zeroverse exists cannot be experimentally tested.
The Universe is at least 93,000,000,000 light years in diameter.
The Universe is at least 13,730,000,000 years old.
The Universe's composition as a whole contains 70% dark energy & 23% dark matter, which we cannot detect and do not understand.
The building blocks of all matter, including our brains, consists of particles which contain 99.9999999999999% empty space.
Our Universe may be one of many (multiverse) or not truly exist at all (zeroverse).